1. Field of the Invention
The present invention relates to a molecular matrix print head for use in a nonimpact printer.
2. Description of the Prior Art
In a well-known nonimpact printing system, information to be printed can be printed on an electrically sensitive ink impregnated recording material by applying an electric field representative of the information to be recorded to the electrically sensitive recording material by means of a printing head associated with the material. There is well known such a printing head including a substrate made of a material having a high resistivity, a plurality of electrodes selectively arranged on said substrate and connected with conductors for feeding the electric signal thereto.
In conventional methods for fabricating such a printing head, with the substrate being made of an insulating material such as ceramic or resin or silica, pin electrodes are provided on the substrate by imbedding fine wires in the substrate, or with the substrate being made of conductive material, electrode styli are provided on the substrate by imbedding fine wires enclosed in glass capillary tubes in the substrate.
It is also known to print conventional copper circuits on flexible printed circuit boards to form electrodes, and to mechanically fasten such boards together in a sandwich to form a print head. The physical dimensions of such a printing head require that the electrode styli formed have minute dimensions such as in the order of less than 0.23 millimeters. Conventional methods as mentioned above have the disadvantages that because of the small dimensions and close tolerances required, the print heads are difficult to fabricate, non-durable and expensive.
A relatively recent innovation in electronic packaging has been the development of the multilayer ceramic (hereinafter MLC) module. In this technology "green" sheets of ceramic powder held together by a temporary organic binder are metallized with a noble or refractory metal, usually, but not mandatorily, applied by screen printing. The metallized sheets are stacked, laminated and fired to form a monolithic ceramic-metal package. Details of MLC technology are given in Kaiser et al., Solid State Technology, May 1972, Volume 15, No. 5, pages 35-40, hereby incorporated by reference.
MLC Technology is well known. U.S. Pat. No. 4,082,906, to Amin, relates to a multilayer ceramic capacitor and process by which a green ceramic tape is cast and silkscreened with silver/palladium metal paste, after which the tape pieces are stacked and laminated to make a monolithic structure. The green chip is then sintered to achieve a fired monolithic multilayer ceramic capacitor.
U.S. Pat. No. 4,192,698, to Maher et al., discloses a method for preparing monolithic ceramic capacitors, including depositing a film of an electroding ink on the surface of each of a plurality of green ceramic layers, then making a stack of the green layers and firing the green ceramic body to mature the ceramic layers and transform the ink into metallic electrode films.
IBM Technical Disclosure Bulletin, Vol. 8, No. 10, March 1966, pages 1307 and 1308, discloses a paste useful in forming capillaries in multilayer ceramic structures. The capillary paste is comprised of a subliming solid that is volatile at or below the green ceramic sintering temperatures but not at the laminating temperature, a vehicle or solvent for the solids and a decomposable metallic resonate. The capillary forming paste is deposited by silk screening on separate green ceramic sheets, which are stacked upon one another and laminated. Upon sintering the laminated sheets fuse into an integral composite which does not disclose a discernible interface between sheets. A molten conductor can then be introduced into the openings formed, thus completing the electrical conductor path in the ceramic.
U.S. Pat. No. 3,235,428, to Naymik, refers to a method of fabricating a unitary array of individual wafers of semiconductor or like material uniformly and intimately bonded together but electrically insulated from each other. By this method, a plurality of semiconductor slices are bonded together using an insulating glass as the bonding medium to produce a bonded structure comprising layers of semiconductor materials separated by thin layers of insulating glass cement. This layered structure is then cut transversely into a series of slices which are again bonded together in similar fashion. The bonded structure is then cut a third time into slices with the result that a series of slices are produced, each of which is composed of an array of individual semiconductor wafers bonded together by a thin vitrious insulating film.
U.S. Pat. No. 3,950,200, to Muramoto et al., discloses a method of fabricating a thermoprinting head by printing a circuit pattern of resistive elements and electric conductors on one surface of a flat paper sheet, covering the circuit pattern and surface of the flat paper with a carrier layer of resin, peeling off the flat paper sheet, placing the remaining carrier layer carrying the circuit pattern over a surface of a preshaped insulating substrate with the circuit pattern being laid downward, and heating the carrier layer placed on the substrate to cause the carrier layer to be burned off and cause a circuit pattern to adhere to the surface of the substrate.
IBM Technical Disclosure Bulletin, Vol. 25, No. 7a, December, 1982, at pages 3527 and 3528, relates to a proposed integrated modular write head for nonimpact printers. The proposed write head described integrates the necessary printing elements and their control circuits and drivers in one package, by employing a suitable module technology, such as MLC. The integration of printing elements and any associated circuitry into a single print head unit containing all requisite elements, is made possible by the low energy, electrochemical printing technology.
A major object of the present invention is to provide a convenient and inexpensive method of fabricating a print head by means of the established multilayer ceramic technology.